Optional Stopping
Definition: T he practice of (repeatedly) analyzing data during the data collection process and deciding to stop data collection if a statistical criterion (e.g. p -value, or bayes factor) reaches a specified threshold. If appropriate methodological precautions are taken to control the type 1 error rate, this can be an efficient analysis procedure (e.g. Lakens, 2014). However, without transparent reporting or appropriate error control the type 1 error can increase greatly and optional stopping could be considered a Questionable Research Practice (QRP) or a form of p-hacking.
Related terms: P -hacking, Questionable Research Practices or Questionable Reporting Practices (QRPs), Sequential testing
Reference: Beffara Bret et al. (2021); Lakens (2014); Sagarin et al. (2014); Schönbrodt et al. (2017)
Drafted and Reviewed by: Brice Beffara Bret ; Bettina M. J. Kern, Ali H. Al-Hoorie, Helena Hartmann, Catia M. Oliveira, Sam Parsons